Establishment of computational dosimetric method for pediatric proton beam therapy

• Project/Area Number: 18K15582
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Gunma Prefectural College of Health Sciences
• Principal Investigator: Takada Kenta 群馬県立県民健康科学大学, 診療放射線学部, 准教授 (10640782)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 陽子線治療 / モンテカルロ計算 / PHITS / 高精度線量評価 / 小児ファントム / 被ばく線量評価 / 二次粒子評価 / 線量評価

Outline of Final Research Achievements

The Monte Carlo code is dose calculation engine that realizes the most accurate dose calculation in radiotherapy. In this research, dose calculation systems of clinically used proton therapy beam for the Monte Carlo calculation were constructed accurately. The constructed dose calculation systems were used to solve potential problems in medical physics for pediatric proton therapy. Especially, the secondary particles generated by the proton therapy beam irradiation were difficult to evaluate by commonly used dose calculation algorithm, the importance of the Monte Carlo calculation were demonstrated. Furthermore, by linking with the research based dose evaluation system, a system that allows visual and quantitative evaluation was constructed.
The computational infrastructure constructed in this research can evaluate the three-dimensional exposure dose in proton beam therapy by particle type. This system is expected to be utilized for safety evaluation in the future.

Academic Significance and Societal Importance of the Research Achievements

今回評価した項目のなかで，陽子線治療ビーム照射に付随して生成する二次生成粒子は，一般に使用されている線量計算アルゴリズムでは評価困難で，モンテカルロ計算コードの有用性が示された．本研究では研究用に開発された線量評価システムとリンクさせることで，その空間分布まで評価できる基盤を構築できたことは極めて意義深く，今後リスク評価等に応用できる．
また，本研究で構築した正確な線量計算体系は，臨床的に使用される陽子線治療ビームのほぼ全てを網羅しており，さらにモンテカルロ計算によって線量のみでなく，ビームの線質を定量的に評価することも可能であるため，今後包括的な線量評価基盤として活用し得る可能性を有している．

Research Products

• [Presentation] Microdosimetric applications using PHITS for proton therapy and BNCT based on full mock-up simulation geometries (2020)
  • Author(s): Kenta Takada, Tatsuhiko Sato, Hiroaki Kumada, Takeji Sakae
  • Organizer: Mini-Micro-Nano Dosimetry and Innovative Technologies in Radiation Oncology 2020
  • Int'l Joint Research
• [Presentation] PHITSを活用したマルチ放射線治療用線量評価システム (2019)
  • Author(s): 高田健太
  • Organizer: 応用物理学会放射線分科会医療放射線技術研究会
  • Invited
• [Presentation] Computational evaluation of dose distribution including radiation exposure to ambient organs for BNCT treatment combined with X-ray therapy or proton beam therapy. (2018)
  • Author(s): Kenta Takada, Hiroaki Kumada, Akira Matsumura, Hideyuki Sakurai, Takeji Sakae.
  • Organizer: 18th International Congress on Neutron Capture Therapy
  • Int'l Joint Research